As CO2 levels are rising in the atmosphere, acidity levels are rising in the ocean, which may be slowing growth rates for coral reefs, oysters, and other shell-building species. Could changes in acidity threaten the survival of oysters in the Chesapeake Bay at a time when oyster farming here is on the rise? To find out more, two researchers have come on a late-June morning to the shore of Maryland's Severn River, not far from the Bay, to set up experiments. To create a kind of time machine, the researchers will pump CO2 into a marked-off square of river water, creating acidity levels as they will be in the future, circa 2050 and 2100. The Severn River project is part of a suite of new and recent research on the effects of rising CO2 levels on the Chesapeake. Whitman Miller is studying how acidifying waters would affect oysters; Tom Arnold is looking at what would happen to seagrasses. more . . .

When the larvae a Mike Congrove's oyster hatchery began dying in large numbers last June, he wasn't sure why. Larval production dropped from 100 million larvae a week down to 10 million. He had worked in the business long enough to know there could be multiple causes. In this dieoff, however, one major change drew his attention: the river water he was using had lower levels of pH. The Piankatank River — at least for awhile — had become more acidic. more . . .

In the Chesapeake Bay and the open ocean, waters with rising acidity may be poison for some species and tonic for others. Recent laboratory studies examined how Bay species were affected by water with different levels of pH, the laboratory scale that describes acidity, and results for oysters and crabs were strikingly different. That's

important because of predictions that the Bay and the open ocean will slowly become more acidic in coming decades. more . . .